Method and apparatus for endometrial ablation

ABSTRACT

An endometrial ablation apparatus and method wherein an RF current having a frequency of between 250 kHz and 100 MHz is passed through the entire surface of an endometrium in order to provide heating of the endometrium. An electroconductive expandable member such as a balloon is used as the medium for passing the current and causing the heating of the endometrium. The temperature of the endometrium is raised to a temperature between 45° C. and 90° C. and preferably not above 70 for a time sufficient to destroy the cells of the lining while maintaining the average temperature of the myometrium at a temperature below approximately 42° C. The expandable balloon is connected to a power source which provides the radio frequency power having the desired characteristics to selectively heat the endometrial lining to the desired temperature. The balloon can be constructed with an electroconductive elastomer such as a mixture of polymeric elastomer and electroconductive particles or can be a non-extensible bladder having a shape and a size, in its fully expanded form, which will extend the organ and effect contact with the endometrial lining to be destroyed. The electroconductive member may consist of a plurality of electrode area segments having a thermistor associated with each electrode segment whereby the temperature from each of said plurality of segments is monitored and controlled by a feedback arrangement from the thermistors.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of application Ser. No. 08/046,683filed Apr. 14, 1993, now U.S. Pat. No. 5,443,470, which is, in turn, acontinuation-in-part of Ser. No. 07/877,567 filed May 1, 1992, now U.S.Pat. No. 5,277,201, issued Jan. 11, 1994.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and an apparatus for in situdestruction of the inner lining of body organs, and more particularlythe providing of a selective destruction of the endometrium as analternative to hysterectomy for treatment of uterine bleeding.

2. Discussion of Background

Prior techniques for removing or destroying the inner lining of bodyorgans have been explored in order to provide for an alternative tosurgical removal of the body organs for treatment of diseases and otherabnormal conditions. Prior techniques involved the destructive treatmentof the inner linings with chemicals and with various forms of thermalenergy such as radio frequency, microwave heating, cryotherapy, lasersurgery and electrosurgery. Radio frequency and microwave energies havealso been applied directly to the linings to generate heat in situ.

One type of thermal destruction is described in U.S. Pat. No. 4,979,949wherein thermal ablation of the mucosal layer of a gall bladder isaccomplished by resistive heating with an RF balloon electrode. Electriccurrent is delivered from the balloon by a conductive expansion liquidfilling the balloon. This device has power loss which occurs in theconductive fluid and it cannot be adapted for anything but a singleelectrode arrangement and it lacks a complete individual power controland/or temperature sensor.

In another example of prior art treatment, balloon catheters have beensupplied with a heated fluid for thermal ablation of hollow body organsas described in U.S. Pat. No. 5,045,056. Furthermore, application ofmicrowave and high frequency RF energy to body areas to destroy bodytissue, using single electrodes enclosed in expanded balloons have beendescribed in U.S. Pat. No. 4,662,383 and U.S. Pat. No. 4,676,258.

The disadvantage of the procedures occurring in the prior art such asdescribed above include a lack of uniform large area treatment becausethese procedures involve a lack of uniform control or temperaturesensing ability to ensure complete ablation.

Other procedures developed to date involve manual applications of smalltreatment tools to successive areas of the lining which is an expensiveoperating room procedure and which, similar to the other previous heatballoon treatments, involve limited assurance of uniform results.

SUMMARY OF THE INVENTION

Accordingly, one object of the present invention is to provide a novelmethod and apparatus for performing safe and rapid endometrial ablationwithout the need for visual contact during the ablation of the lining.

It is a further object to provide an apparatus and a method forendometrial ablation which can be carried out on an out-patient basiswithout requiring the use of an operating room.

The objects of the invention are carried out by a method which utilizesan electrically conductive or conductively coated expandable memberconforming to the inner surface of the endometrium. The expandablemember is filled with an electrically non-conductive medium and a RFcurrent is passed through substantially the entire surface of theendometrium. The current is sufficient to resistively heat theendometrium in a single operation to a temperature within a range ofbetween 45° C. to 90° C. for a time sufficient to destroy the cells ofthe lining while maintaining the average temperature of the myometriumat a temperature of substantially 42° C. or less. The RF current has afrequency of at least 250 kHz and less than 100 MHz.

The method according to the present invention involves the insertion ofa conductive, expandable member in its unexpanded state into the uterinecavity through the cervical opening and subsequently expanding themember to establish surface contact with the endometrial surface andapplying the RF current to the member in its expanded condition.

It is a further object of the present invention to provide that theelectroconductive expandable member includes a thin bladder having anarray of separate electrodes on one surface and further having atemperature sensor associated with each separate electrode in order toprovide a feedback temperature sensor for each electrode. The pluralityof separate electrodes are independently and sequentially energized withthermistor temperature feedback to bring the endometrial temperature toa desired level.

It is further an object of the present invention to provide electrodeshaving a specific configuration so that the heating is not concentratedat the edges of the electrode and so that uniform heating is achievedover the entire electrode surface by providing a plurality ofthroughholes throughout the electrode or by forming the electrode in apattern of lines, thereby creating a uniform density of edges andequalizing the current density across the surface area of the electrode.

It is a further object of the present invention to provide an electroniccontrol means capable of controlling the output of a conventionalelectrosurgical power source and delivering power from the power sourcesequentially, and in a controlled manner, to the electrodes of theballoon.

It is a further object of the present invention to provide a disposablehandheld applicator and electrode assembly combination to deliver theablation device to the uterus and to retract the device upon completionof the ablation.

It is a further object of the present invention to provide an array ofseparate electrodes and associated separate thermistors on an expandablemember with a series of power leads with each power lead deliveringpower to a single electrode and to its associated thermistor to providea temperature feedback for temperature regulation of the endometrialablation.

It is a further object of the present invention to provide an innerlumen having the ability to contain a fiber optic image conduit whichserves as a visual aid when placing the device.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is a cross-sectional representation of an electroconductiveballoon as an expandable member in an expanded format in place in auterus;

FIG. 2 is a representation of the apparatus of FIG. 1 in an unexpandedcondition;

FIG. 3 is an enlarged cross-section illustrating the relationshipbetween a small segment of the uterine endometrium and the expandedmember;

FIGS. 4a-b is a representation of an embodiment of an expandable memberwhich uses a plurality of surface segments with each surface segmenthaving a separate conductive surface and a temperature sensor;

FIG. 5 is a schematic representation of the power control system for themulti-segment element shown in FIG. 4;

FIG. 6 illustrates an embodiment of the multi-segment element havingperforated electrodes with illustrated power traces on the outsidesurface of the expandable member;

FIG. 7 illustrates thermistor traces and circular wiring jumper mountingpads on the interior of the expandable member;

FIGS. 8a and 8b illustrates the double-sided electrode/thermistor traceson the respective inside and outside portions of the expandable memberof FIGS. 6 and 7;

FIG. 9 illustrates an embodiment utilizing flat metallized stockmaterial to be adhesively bonded to the expandable member with thematerial being arranged in a serpentine configuration;

FIGS. 10a-b show the bladder device for delivering the expandable memberto the uterus;

FIGS. 11a-c show the bladder device of FIG. 10 in a retracted positionand illustration of the deflated expandable member;

FIG. 12 schematically represents the connection of the bladder device tothe power generation source and testing structure;

FIG. 13 is a schematic of an embodiment of the temperature measurementcircuitry of FIG. 5; and

FIG. 14 is an equivalent of FIG. 13 showing effective tissue shunting.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, and moreparticularly to FIG. 1 thereof, a cross-sectional representation of theinvention utilizes an electroconductive balloon as the expandable memberwith FIG. 2 representing the same apparatus as FIG. 1 prior to inflationof the balloon element. The uterus 2 consists of myometrial tissue 4surrounding the uterine cavity. The normal uterine cavity or envelope isa flat cavity having approximately the shape of an inverted trianglewith the two upper corners communicating with the ovaries by way of thefallopian tubes 6 in the bottom corner opening into the cervical canal8. The entire surface of the envelope includes the entrance of thefallopian tubes 6 and the cervical canal 8 which is covered with a thinlayer of tissue known as uterine endometrium. The selective destructionof the endometrial cells is the goal of the improved method andapparatus disclosed in this present invention.

The monopolar electrode system developed in conjunction with FIG. 1expands to conform to the endometrial surface to be treated and this inturn dilates and stretches the endometrium to reduce surface folds.Radio frequency electric current passes through the dilated endometrialsurface for a time sufficient to destroy the endometrial cells byelevating the temperature of the endometrium to between 45° C. and 90°C., and preferably within 10 seconds. The temperature is maintaineduntil the endometrial tissue is destroyed which is optimallyaccomplished by a temperature between 55° C. to 65° C. for up to 10minutes.

The electric current passes through or along the surface of theexpandable member and the interior of the expandable member is filledwith an electrically nonconductive substance such as a fluid or gas. Theexpandable member can be any material or article which can be compressedor otherwise prepared in a small diameter configuration for insertionthrough the cervix and expanded or inflated after insertion to providethe dilation. This expandable member establishes direct electricalconnection or capacitive coupling with the endometrium. A secondelectrical contact can occur by way of grounding plates or patches whichcontact a large area of the patient's skin in order to complete theelectrical circuit.

Electric current flowing through the tissue causes resistive heating.The power density diminishes with distance from the electrode as thereciprocal of the fourth power of the distance. Thus, any heat generatedis focused in the endometrium and the immediately surrounding musculartissue which in the particular case of the present invention is theportion of the myometrium in contact with the lining. Because themyometrium 4 is highly vascularized, heat removal occurs rapidly. As aresult, the temperature of the endometrium 12 can be heated to adestructive temperature faster than the myometrium 4 and the rest of theuterus. Therefore, because of this temperature relationship, endometrialablation can be safely accomplished as a simple medical procedure usinglocal anesthesia. Furthermore, it can be a service made available at afraction of the cost of prior art systems with less hazard than otherendometrial ablations.

The inflatable balloon or bladder 14 is inserted into the uterine cavity15 as shown in FIG. 2 and subsequently the inflation of the balloonoccurs with a gas or a nonconductive liquid so that it extends and fillsthe uterine cavity conforming to the expanded surface as shown inFIG. 1. Portions of the balloon 14 extend into the entrance to thefallopian tubes 6 and extend along the entire endometrial surface 12 tothe cervix 8. The balloon is attached to and forms a fluid-tight sealwith the tube 16 which encloses a smaller fluid delivery tube 18 as wellas an electrical cable 20 containing leads for the conductor as well asadditional leads for the sensors. A plurality of temperature sensors 24are shown attached to the inner surface of the balloon. Alternatively,this lead configuration can be replaced by lead pairs 22 for eachsensor. The temperature sensors 24 are conventional thermistors orthermocouples and are positioned on zones of the balloon which willcontact areas of the endometrial surface which are most sensitive tooverheating. The temperature sensors can also be fiber optic temperaturesensors. The fluid delivery tube 18 is connected to a source of gas orliquid through a conventional fluid control system which will be laterillustrated in conjunction with FIG. 13.

The FIG. 3 is an enlarged cross-section illustrating the relationshipbetween a small segment of uterine endometrium and the expandableballoon element of the FIG. 1. The endometrial lining 12, supported onthe myometrium 4, is typically an irregular surface even after it isextended by the inflated balloon 14. Electrical contact between theconductive surface 35 on the outer surface of the balloon 14 and theendometrium 12 can be improved by covering the outer surface of theballoon 14 with a conventional electroconductive solution, paste or gel37 which is physiologically non-toxic and non-irritating. Suitableelectroconductive media including the known types of gels and pastesused as surface coatings for defibrillators may be used. Examples ofsuitable conductive gels are carboxymethylcellulose gels made fromaqueous electrolyte solutions such as physiological saline solutions andthe like. The electroconductive solution, paste or gel enhanceselectrical contact between the balloon and the endometrium by fillingthe pores of the balloon surface and the irregularities in theendometrial surface.

The expandable balloon or bladder can be an elastomeric polymer such asa natural or synthetic rubber made conductive by mixing the polymer withelectroconductive particles such as carbon or conductive metalparticles. Alternately, it may be made conductive by a surface coatingof electroconductive material such as an electroconductive gel, or aconductive metal coating on the outer or inner surface of the balloon orbladder wall. Electroconductive coating can be applied to organicpolymer surfaces by conventional vapor deposition, electricaldepositions, sputtering and the like.

A preferred balloon comprises a thin, non-extensible polymer film suchas a polyester or other flexible thermoplastic or thermosetting polymerfilm, for example, having a conductive metal coating on the outer orinner surface thereof. The films form a non-extensible bladder having ashape and size, in its fully expanded form, which will extend the organand effect contact with the endometrial lining to be destroyed. Theinner surface of the non-extensible bladder can be coated withelectroconductive material which will capacitively couple to theendometrium provided that the bladder wall thickness is less thanapproximately 0.25 mm.

The surface of the expandable member can be an open-cell, porousmaterial such as a foam or similar caged network of material which canhold a quantity of the electroconductive solution, paste or gel requiredto secure satisfactory electrical contact with the opposed endometrialsurface. The surface can be coated with or impregnated with theelectroconductive substance.

FIG. 4 illustrates an embodiment using a balloon with a plurality ofsurface segments as the expandable bladder 39. Each of the surfacesegments has a conductive surface and a temperature sensor. In thisparticular embodiment, the balloon has a segmented electrode coating ofelectroconductive metal on either the inner or the outer surface topermit controlled delivery of power to each segment. Each segment 40 iselectrically connected through conventional leads to a power source (notshown in FIG. 4). Each conductive segment 40 also has a thermistor 42which is connected through conventional leads to a switch matrix. FIG.4B illustrates a top view of the bladder 39 and particularly features alumen 44 extending through the center of the bladder 39. The lumenallows for light guides to be inserted through the center of theelectrode. In other words, there is an inner lumen tube 44 attached tothe center of the flat film.

FIG. 5 is a schematic representation of the power source controller andthe switch matrix for the multi-segment balloon discussed above inconjunction with, for example, FIG. 4. The electrical leads connect tothe electro-thermistor pairs of the bladder of FIG. 4 by way ofconnectors 138 as shown in FIG. 5. The thermistor leads are connected tothe matrix switch bank 134 and the electrode leads are connected to theswitch bank 136. Each thermistor (FIG. 4a) 42 is sampled by means of thetemperature measurement circuitry 128 and the isolation amplifier 126before being converted in the converter 116 and fed to the computer 114.The temperature measurement circuitry compares the measured temperaturewith a thermistor reference voltage 132. The electrode switch 136 iscontrolled in response to the output of the computer 114 by means of theopto-isolators 130. Input power from the RF input passes through theovervoltage and overcurrent protector 110 and is filtered by thebandpass filter 122 before being subjected to overvoltage suppression bythe suppression unit 124. The voltage is isolated by means of thetransformers 139, 140 and 142 with the transformer voltages V_(i) andV_(v) from the transformers 140 and 142 being converted by the RMS-DCconverters 118 into an RMS voltage to be fed to the converters 116.Prior to conversion, the signals V_(i) and V_(v) are also fed to ahigh-speed analog multiplier 120 RF control from computer 114 isprovided through interface 112.

A variation of the electrode structure of FIG. 4 is shown in FIG. 6wherein there are perforated electrodes 150 illustrated with their powertraces 152. This particular electrode bladder of FIG. 6 is shown withthe perforated electrode 150 on the exterior of the bladder.

FIG. 7 illustrates thermistor common-side traces 154 on the interior ofthe bladder with circular wiring jumping pads 156 with mounting sites157 serving as the base for the thermistors. The common-side tracesprovide power for both the electrodes and the associated thermistor. TheFIG. 7 illustrates both interior sides of the bladder.

FIGS. 8a-b illustrates both the outside and the inside of a double-sidedelectrode with thermistor traces having perforated electrodes 160 on theoutside and thermistor wiring pads 162 and electrode power leads 164 aswell as thermistor mounting sites 166 on the inside. The connectionbetween the inside and outside of the bladder is shown by the continuitylabeled Via in the FIGS. 8a and 8b. FIG. 8b specifically shows across-sectional view of the bladder with the electrode 160 on the top oroutside surface and the power traces 164 and thermistor wiring pad andmounting site 166 on the lower or inside surface. FIG. 8b illustratesthe mounting of the thermistor 163 on the mounting site 166 with aconnection between the power trace 164 and the thermistor 163 being madeby the thermistor lead 169. FIG. 8b clearly illustrates that all exceptone of the holes in the perforated electrode 160 have a depth whichreaches to the substrate or bladder 174. The one hole labelled Viaextends through the entirety of the bladder as an electrical connectionbetween the perforated electrode 160 and the power trace 164 on thebottom or inside surface. The FIG. 8a embodiments corresponds to acombination of the inside illustration of the power traces and thebonding surfaces from FIG. 7 along with the perforated electrode of FIG.6 with the exception that FIG. 8a has the power traces on the insidesurface whereas the embodiment of FIG. 6 has the power traces for theperforated electrodes on the outside surface.

Each of the views of FIGS. 6, 7 and 8, whether on the inside or theoutside must be understood to represent only two surfaces of a bladderwhich must necessarily have four surfaces. The bladder, prior toinflation, can be envisioned as triangular with two outside triangularsurfaces (top and bottom) and two inside triangular surfaces prior toinflation.

A further variation of the electrode structure is shown in FIG. 9 whichillustrates a flat metallized stock material adhesively bonded aselectrodes 170 and 172 to the outside of both the top and the bottom ofthe bladder. The electrodes, which are metallized and adhesively bonded,form a serpentine electrode pattern in order to promote uniform heatingof the area.

FIGS. 10a and 10b illustrate the bladder application device which isused to insert the bladder electrode constructed in accordance with anyone of the embodiments discussed above. FIG. 10b is a side view of theapplication device illustrating a sheath applicator with a main tube anda shrink wrap covering the wiring leads. A fiber bundle is located inthe center of the applicator which would be connected through the lumenillustrated in FIG. 3, for example. The applicator device 175 has aninflation inlet 176 and an electrode wiring insertion port 177 as wellas the optical viewing fiber inlet 178 through a lumen. Movement of thebladder electrode 180 is controlled by the alignment guide and thesheath retraction knob 181 acting in conjunction with a thumb detent182. The applicator of FIG. 10a shows the bladder electrode in anextended but unexpanded position.

The FIGS. 11a-c illustrate the bladder device of FIG. 10 in a retractedposition with FIGS. 11b and 11c being taken at the cross sections titledA-A' and B-B' respectively. FIG. 11c illustrates the position of thedeflated bladder with respect to the main tube in the retracted positionat line B-B'. The remaining features of the applicator 175 remain asindicated with respect to FIG. 10.

An illustration of the connection of the application device 175 and theelectrode balloon 190 in accordance with any one of the embodiments ofthe FIGS. 6-9 is illustrated in FIG. 12. An inflation pump 193 providesthe medium for the expansion of the balloon 190 while the electrode belt195 provides the reference electrode for connection to the controlsystem 100. RF generator 197 serves as the RF input power for thecontrol system schematic of FIG. 5 by means of electrosurgical interfacecables 199. The control module 203 and interface control 204 connectwith computer 114.

Once the electrode system and the control system of FIG. 12 and FIG. 5are connected, the RF electrodes are separately, independently andsequentially energized with thermistor temperature feedback to bring theendometrial temperature up to a desired level. The system accomplishesthis in an automated manner based upon the output from the RF generator197 which is a conventional electrosurgical power supply. As discussedpreviously, the electrodes may have a variety of specific configurationsand heating is concentrated in the endometrium at the surfaces of theelectrodes due to the various illustrated electrode configurations inorder to provide uniform heating. An example of the concentration of theheat over the entire surface of the electrode is available from theembodiment wherein holes are provided through the electrode as shown inFIGS. 6 and 8. Uniform heating is also obtained by extending theelectrodes in a pattern of lines such as the serpentine patternstructure of FIG. 9.

As a result of these kinds of constructions, the treatment method of thepresent invention as well as the electrode elements provide an increasedcurrent density as a function of the "electrode edge length" availablefor heating. Furthermore, as discussed previously, the electrodes can beon the outer surface of the bladder while the power traces, thermistors,and thermistor leads can be on the other surface of the bladder.

In the embodiments of FIGS. 6-9, the various electrode pattern featurecommon power traces for both the electrodes and the associatedthermistors. That is, one power lead provides the power for anindividual electrode as well as its associated thermistor thereby savingin the construction of the bladder electrodes by reducing the number ofrequired thermistor leads by one-half. In such embodiments, eachelectrode has a corresponding thermistor lead in common with the RFpower lead. The second leads from all thermistors are then connectedtogether to form a thermistor common as shown for example in the FIGS. 7and 8a. This arrangement provides the advantage that it only requiresN+1 leads to drive an ablation balloon with N electrodes and Nthermistors. Because of this construction, however, the temperaturemeasurement circuitry 128 of FIG. 5 has additional requirements beyondthe construction with a separate power lead for each thermistor and foreach individual electrode. The construction with separate power leadsfor the electrodes and the thermistor are well known and any one of avariety of temperature measurements schemes for individual electrodescould be utilized.

The specialized requirements brought about by using a common power leadfor each electrode and each thermistor are met by the embodiment shownin the FIG. 13. In FIG. 13, RF power is selectively applied throughswitch matrix 210 so that it can be applied to selected electrodes. Theelectrode/thermistor circuitry is represented on the right hand side ofthe Figure generally as 220 with a particular example being given bythree electrodes and three thermistors represented by resistors 222, 224and 226. A reference voltage Vref is buffered by an operationalamplifier follower 232 and passes through resistor 233 before enteringthe measurement switch matrix 240. The output of resistor 233 isbuffered by operational amplifier 234. Outputs of the measurement switchmatrix 240 are fed through the filters 244, 246 and 248 which representlow pass filters which block high frequency RF but pass DC and very lowfrequency voltages.

The balloon thermistor common lead 227 passes through the filter 249 toground.

During operation, RF power is applied to a particular desired electrodeor electrodes by operations of the RF power switch matrix 210.Measurement of thermistor resistance 222, 224 or 226 is independent ofthe particular electrodes connected to the RF power. In order to providea measurement of RT1 (222), measurement switch matrix 240 is set up toconnect lead 1 to the right hand side of resistor 233 while all otherleads are set to be connected to the output of the follower 234. Thisparticular set up and arrangement forces the voltage VT to be equal toVREF. RT1/(Rb+RT1). Therefore this allows the measurement of RT1 due tothe known value of Rb and VREF. Because the other leads 2, 3 from thecircuitry 220 are held at the same voltage by the follower 234, thereare no voltage differences between any of these leads and therefore nocurrent will flow between them.

This lack of a current between leads is extremely important because thetissue which contacts the electrodes cause an effective shunt currentpath that would otherwise affect the measured voltage VT, without thecircuitry of FIG. 13.

This effective shunting by the tissue is illustrated by the equivalentcircuit of FIG. 14 which shows effective tissues resistances 253 and 254connected between electrodes 261, 262 and 263.

The bladder electrodes are constructed in accordance with a methodwherein a double-sided thin flat film is plated on one side to increasethe electrode thickness and a deposit mask is provided for an electrodepattern on the thick side using lithographic techniques. Then a mask isdeposited for the conductors which lead to the temperature sensingelements on a second side. Subsequently, non-masked conductors areetched away leaving the desired pattern. In an alternate embodiment, theconductive patterns for the electrodes and conductors leading to thetemperature sensing elements could be directly deposited using vapor orother deposition techniques.

The thermistors (FIG. 4a) 42 are provided using surface mountingtechniques and the attached inner lumen is provided at the center of theflat film. The balloon is then folded and sealed to the main tube at theproximal end with the inner and outer concentric tubes sliding withrespect to each other as illustrated in the FIG. 10. Subsequently,conductors are brought to the outside of the main tube to the end of thedevice near the handle of the applicator. The outer tube is placed overthe conductor and heat-shrunk as shown in FIG. 10b. Finally, the handleof the applicator of FIG. 10 or FIG. 11 is assembled.

Other forms of providing an electrode balloon may be used such asutilizing a blow molded preform or the formation of the balloon withcopper on polyimide conductive elements on the surface of a compliantballoon. Furthermore, this balloon may be formed as a "sock" to fit overthe inner latex balloon with the sock being a compliant device. Otheranticipated forms of an electrode balloon structure include the use ofthe plated or etched wiring all the way from the balloon itself down tothe handle.

Utilizing the present invention allows for the use of low accuracythermistors wherein calibrations can be stored in memory chips in thehandles of the device. The attachment of the electrodes to the bladdercan be accomplished by conductive adhesive or by soldering.

The applicator of FIGS. 10 and 11 can be deployed by pulling the frontend of the balloon back inside and collapsing the balloon around it. Inorder to expedite the deployment, the pattern can be formed withparticular kinds of spines for the sheath in order to aid in the foldingof the patterned electrode within the applicator.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. An ablation apparatus for selectivelydestroying tissue of a hollow body organ, said apparatus comprising:anelectroconductive, expandable electrode means for effecting electricalcontact with an inner surface of the organ, said expandable electrodemeans being a bladder provided with a plurality of separate electrodeson a surface of the bladder; a plurality of temperature sensors, whereina temperature sensor is associated with each electrode and is mounted inclose proximity to its associated electrode; a radio frequency powermeans connected to said expandable electrode means for selectivelyproviding power to said electrodes to heat said tissue by passingcurrent through the tissue; and control means for controlling the powermeans to heat the selected tissue to a uniform temperature of at least45° C.
 2. The apparatus according to claim 1, further including atemperature measurement circuitry including a first switch matrix meansfor selectively applying RF power to at least one of said plurality ofelectrode power leads, a first reference voltage point, a secondreference voltage point and a second switch matrix means for connectinga selected one of said plurality of electrode power leads to said firstreference voltage point while simultaneously connecting all other onesof said electrode leads to said second reference voltage point.
 3. Anablation apparatus of claim 2, wherein the bladder is a non-extensiblebladder.
 4. An ablation apparatus of claim 1, wherein the control meansis a means for controlling the power means to heat the selected tissueto a uniform temperature within the range of from 45° to 90° C.
 5. Anelectrically conductive expandable electrode assembly for providingelectrical contact with an inner surface of a hollow body organ for thepurpose of ablating tissue of the organ, said assembly comprising:anexpandable bladder having an inner surface and an outer surface, one ofsaid inner and said outer surface being provided with a plurality ofseparate electrodes and the other of said inner and outer surface beingprovided with a plurality of thermistors corresponding to each of saidplurality of electrodes.
 6. An electrode assembly of claim 5, whereineach of said plurality of electrodes further comprises a plurality ofholes, with one of said plurality of holes of each electrode extendingthrough said bladder from said outside surface to said inside surface,and said extended holes providing electrical continuity between saidelectrodes and said other surface, said other surface further includinga plurality of power leads, each lead being electrically connected to acorresponding one of said electrodes, said leads each extending from oneextremity of said bladder to a respective one of said extended holes,each said power lead also extending to a respective one of saidthermistors, whereby the relationship between the plurality of holes ineach of said electrodes and said power leads provides for uniformheating on a surface of each of the respective electrodes.
 7. Theexpandable electrode assembly according to claim 5, wherein each of saidthermistors is further connected to a common ground lead on said othersurface.
 8. An ablation method for selectively destroying selectedtissue of a hollow body organ, comprising the steps of:a) passing aradio frequency current through the selected tissue from an expandableelectrode member conforming to the inner surface of the organ, theexpandable electrode member including an expandable bladder, a pluralityof electrodes mounted on the bladder, and a plurality of temperaturesensors, wherein a temperature sensor is associated with each of saidelectrodes and is mounted in close proximity to its associatedelectrode; and b) controlling the current from each electrode usingfeedback from said plurality of temperature sensors to uniformly heatthe selected tissue in a single operation to a temperature of at least45° C.
 9. An ablation method for destroying lining of a body organhaving a supporting mass under the lining, said method comprising thesteps of:passing a radio frequency current having a frequency of atleast 250 kHz from an expandable member conforming to the lining andfilled with expansion medium, wherein said current is passed through aportion of the lining to resistively heat in a single operation theportion of the lining to a temperature of at least 45° C. for a timesufficient to destroy cells of the lining while maintaining an averagetemperature of the supporting mass at a temperature below approximately42° C.
 10. The method of claim 9, wherein the body organ is a uterus,the lining is the endometrium of the uterus, and the supporting mass isa myometrium of the uterus.
 11. The method of claim 9, wherein saidportion of the lining includes the entire lining.
 12. A method of claim9, further comprising monitoring the temperature of the lining andreducing said current when said monitored temperature exceeds apredetermined value.
 13. An ablation apparatus for selectivelydestroying lining of an organ in a body, having an outer surfacecomprising an electro-conductive, expandable electrode means whichincludes a non-extensible bladder having a shape and size, in its fullyexpanded form, which will extend the organ and effect contact with thelining to be destroyed and an external electrode means adapted tocontact the outer surface of the body, the expandable electrode meanscontaining an expansion medium, the non-extensible bladder having aninner surface that is coated with electroconductive material and a wallthickness of less than about 0.25 mm; and a power source connected tothe expandable electrode means and to the external electrode means, thepower source being adapted to provide radio-frequency electric power tothe expandable electrode means at a frequency of at least 250 kHz in anamount which, when current is passed from the expandable electrode meansthrough the lining, will heat the lining of the organ to a temperatureof at least 45° C.
 14. An ablation apparatus for selectively destroyingtissue of a hollow body organ, said apparatus comprising anelectroconductive, expandable electrode means for effecting electricalcontact with an inner surface of the organ, said expandable electrodemeans including an expandable balloon and a plurality of electrodes on asurface of the balloon;a plurality of thermistors, each associated withone of said plurality of electrodes; an external electrode means forattachment to an outer surface of the body; a radio frequency powermeans connected to said expandable electrode means and the externalelectrode means for providing power to said electrodes; and a pluralityof electrode power leads each of which being electrically connected to arespective one of said plurality of electrodes and a respective one ofsaid thermistors.